1. Technical Field
The present disclosure generally relates to photo-multiplier tubes (PMTs). In particular, the present disclosure relates to a tool and process for the removal of PMTs during the refurbishment and/or repair of photo-detectors or photo-sensors.
2. Background of Related Art
Nuclear medicine is a unique medical specialty wherein radiation is used to acquire images which show the function and anatomy of organs, bones or tissues of the body. Radiopharmaceuticals are introduced into the body, either by injection or ingestion, and are attracted to specific organs, bones or tissues of interest. Such radiopharmaceuticals produce gamma photon emissions which emanate from the body and are detected by a radiation detector, such as a positron emission tomography (PET) camera.
Conventional PET cameras utilize a scintillation crystal, which absorbs the gamma photon emissions and emits light photons (or light events) in response to the gamma absorption. An array of photo-detectors, such as photo-multiplier tubes (PMTs), is positioned adjacent to the scintillation crystal. The PMTs receive the light photons from the scintillation crystal and produce electrical signals having amplitudes corresponding to the amount of light photons received. The electrical signals from the photo-multiplier tubes are applied to position computing circuitry, wherein the location of the light event is determined, and the event location is then stored in a memory, from which an image of the radiation field can be displayed or printed.
The PMTs are frequently removed during refurbishment and/or repair of the detectors via a PMT removal tool. One such removal tool resembles a gardener's trowel or a painting knife. A gardener's trowel is described in the prior art as shown and described by U.S. Pat. No. 5,327,612. A trowel 11 is constructed from a flat metal blade 13, a metal shank 15, and a handle 17. Shank 15 is integrally formed with, or is otherwise secured to, the top surface of blade 13. Shank 15 extends upwardly from the top surface of the blade providing a metal handle tang 19 which serves as the support structure of handle 17. Tang 19 extends distally from shank 15 and is raised above the plane of blade 13 in a generally parallel disposition thereto. Blade 13, shank 15 and tang 19 are typically forged of metal as one piece. The distal end of the flat metal blade 13 is preferably a sharp edge for allowing the user of the trowel 11 to separate and loosen the gel between a PMT and a metal shield.
However, this method of using a gardener's trowel or a painting knife can cause severe damage to the PMTs during the removal process. The sharp edge of the trowel is preferably inserted into a notch on a plastic end cap located on a top portion of the PMT assembly. Once the edge of the trowel is inserted into the notch, the user of the trowel applies variable forces to the PMT in order to loosen the PMT from the gel adhesive bond securing the PMT to the tube shield. The variable forces applied to detach the PMT can easily damage PMTs during the refurbishment and/or repair of the detectors.
Therefore, a need exists to provide for a more precise tool and process for the damage-free removal of PMTs during the refurbishment and/or repair of detectors.